Afibrinogenemia, Congenital

Synonyms of Afibrinogenemia, Congenital

Congenital Afibrinogenemia

General Discussion

Congenital Afibrinogenemia is a rare disorder characterized by absence of a certain substance (protein) in the blood that is essential in the blood clotting (coagulation) process. This protein is known as fibrinogen or coagulation factor I. Affected individuals may be susceptible to severe bleeding (hemorrhaging) episodes, particularly during infancy and childhood. Congenital Afibrinogenemia is thought to be transmitted as an autosomal recessive trait.

Signs & Symptoms

Congenital Afibrinogenemia is a very rare blood disorder in which the patient is born with little or no fibrinogen in the circulating blood. Fibrinogen is a protein that is needed to form blood clots. When this protein is absent, the blood does not coagulate which can cause the patient to hemorrhage.

Two thirds of the patients with Congenital Afibrinogenemia have bleeding problems from infancy on. The severity and frequency of bleeding from surgery or trauma can vary from mild to severe.

Infants may have severe hemorrhaging during the first few days of life. Typically the hemorrhaging can be noticed from the umbilical cord, in the stools, when vomiting, after circumcision, from the use of forceps during delivery and/or in collections of blood that become trapped in the skin tissue (hematomas).

Other symptoms of Congenital Afibrinogenemia may be severe bleeding after minor trauma, the loss of baby teeth, or during the extraction of teeth. Patients may also bruise easily and hemorrhage from the gums.

Some patients with Congenital Afibrinogenemia also experience hemorrhaging into a joint (hemarthrosis), nosebleeds, gastrointestinal bleeding, heavy bleeding during menstruation; bleeding in the chest cavity and/or a ruptured spleen.

Causes

Congenital Afibrinogenemia is thought to be transmitted as an autosomal recessive trait. Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother.

In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal (for that particular trait). The risk is the same for each pregnancy.

Absence or deficiency of fibrinogen is thought to result from abnormal changes (mutations) of one of three genes, known as the fibrinogen alpha-chain (FGA), beta-chain (FGB), or gamma-chain (FGG) genes. These genes have been mapped to the long arm (q) of chromosome 4 (4q28). Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males and two X chromosomes for females. Each chromosome has a short arm designated as “p” and a long arm identified by the letter “q”. Chromosomes are further subdivided into bands that are numbered.

According to one team of researchers, genetic analysis of individuals with congenital afibrinogenemia within one extended family (i.e., including two siblings and two first cousins) revealed deletion of genetic material from the fibrinogen alpha-chain gene (FGA) on both chromosomes (homozygous deletion). Because previous studies have not detected this homozygous deletion, the study’s researchers indicate that other genetic abnormalities (mutations) may play some role in causing the disorder in some affected individuals.

Affected Populations

Congenital Afibrinogenemia is a rare disorder that affects males and females in equal numbers. Approximately one hundred and thirty cases have been recorded in the medical literature.

Related Disorders

Symptoms of the following blood clotting disorders can be similar to those of Congenital Afibrinogenemia. Comparisons may be useful for a differential diagnosis:

Factor IX Deficiency is a severe genetic bleeding disorder that resembles classic Hemophilia A. Factor IX is a component of the blood clotting substance thromboplastin. It is deficient at birth in patients with this disorder. Factor IX Deficiency varies in severity between families and occurs most often among males. In rare instances, female carriers have been known to exhibit this deficiency in a mild form. Symptoms include prolonged bleeding episodes, and in very severe cases, joint pain and bone deformities. (For more information on this disorder, choose “Factor IX Deficiency” as your search term in the Rare Disease Database.)

Factor XIII Deficiency is a very rare inherited disorder that prevents the blood from clotting normally. The lack of clotting factor XIII can cause slow, oozing internal bleeding which may begin several days after even a mild trauma, such as a bump or bruise. The bleeding may persist so that large cysts form in the tissue spaces, destroying the surrounding bone and causing peripheral nerve damage. This typically occurs in the thigh and buttocks area. (For more information on this disorder, choose “Factor XIII Deficiency” as your search term in the Rare Disease Database.)

Hageman Factor Deficiency is a rare genetic blood disorder. It is caused by a lack in activity of the Hageman factor in blood plasma, a single-chain glycoprotein which is also called Factor XII. This factor is needed for blood clotting. However, when it is deficient, other blood clotting factors tend to compensate for Factor XII. This disorder usually presents no symptoms and is only accidentally discovered through pre-operative blood tests that are required by hospitals. (For more information on this disorder, choose “Hageman Factor Deficiency” as your search term in the Rare Disease Database.)

Hemophilia is a hereditary blood clotting disorder which affects males almost exclusively. Hemophilia is caused by the inactivity of one of the blood proteins necessary (usually Factor VIII) for clotting and can be classified by its level of severity, mild, moderate, and severe. Severity is determined by the percentage of active clotting factor in the blood. (For more information on this disorder, choose “Hemophilia” as your search term in the Rare Disease Database.)

Von Willebrand Disease is a hereditary blood clotting disorder characterized by prolonged bleeding. Blood clotting is slow due to a deficiency of the Von Willebrand factor protein and factor VIII protein (the factor VIII complex). Also, platelets do not stick normally causing excessively slow clotting time. Increased risk of excessive bleeding following surgery, dental procedures or injury occurs in patients with this disorder. With proper treatment and appropriate precautions, few patients become seriously handicapped by Von Willebrand Disease. The tendency to prolonged bleeding usually decreases with age. (For more information on this disorder choose “Von Willebrand” as your search term in the Rare Disease Database)

Standard Therapies

Patients with Congenital Afibrinogenemia may be treated with infusions of cryoprecipitate concentrates. This is prescribed to raise the fibrogen level in the blood permitting clots to form.

Fibrogen concentrates may be given but there is a risk of contracting an infectious disorder. Cryoprecipitate is the preferred treatment.

Genetic counseling may be of benefit for patients and their families. Other treatment is symptomatic and supportive.

Investigational Therapies

Research on birth defects and their causes is ongoing. The National Institutes of Health (NIH) is sponsoring the Human Genome Project which is aimed at mapping every gene in the human body and learning why they sometimes malfunction. It is hoped that this new knowledge will lead to prevention and treatment of genetic disorders in the future.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

Years Published

1993, 1999, 2007

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